Googling "Finding drive info with Perl" pointed me to Win32::DriveInfo. Win32::DriveInfo::DrivesInUse() will tell you what drives exist. There are also functions to give you info on each drive, as well as to tell you what drive letters are still available.

Thanks for that. I did try the Perl in the link but sadly I did not have the required Win32::DriveInfo.
However I did use your google search and found a page which explained where the drive letters are in the registry.
The following Perl gives what I wanted.
It works for XP but I do not know about other Windows OS

use strict "vars";

my (%dletters, $return_code, $return_message, $jl);

sub drive_letters_find($$$) {
##-------------------------------------------------------------------
## this gets the drive letters and their paths for the current PC
# it returns a has where key is drive letter - value is it contents
## ------------------------------------------------------------------

my ($ref_dletters, $ref_return_code, $ref_return_message) = @_;

my ($pp, $k, $key, $vals, $CurrVer, %vals);

use Win32::Registry;

$pp = "Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\Map Net
+work Drive MRU\\";

$$ref_return_code = $main::HKEY_CURRENT_USER->Open($pp, $CurrVer);

if($$ref_return_code == 1) {

    $$ref_return_message = 'drive letters found';

    $CurrVer->GetValues(\%vals);
    foreach $k (keys %vals) {
        $key = $vals{$k};

        $ref_dletters->{$$key[0]} = $$key[2];
    }    
} else {

    $$ref_return_message = "Could not open regsitry $pp\n\n";
    
}

}

drive_letters_find(\%dletters, \$return_code, \$return_message);

print "\nafter drive_letters_find\nresult code <$return_code> message 
+<$return_message>\n";
if($return_code == 1) {
    print "mapped drive letters found\n";
    foreach $jl (sort {$a cmp $b} keys %dletters) {
        print "letter <$jl> path <$dletters{$jl}>\n";
    }
}
[download]

use Win32::FileOp qw(Mapped);
my $share = Mapped 'M:';

my %shares = Mapped();
[download]

You should give the code in the following node by Marshall a try.

It should do exactly the thing you want.

Rata